Missouri hellbenders bounce back from the brink of extinction

By Hannah Lazo

ST. LOUIS – On a typical Tuesday at the St. Louis Zoo Herpetarium, a steady stream of visitors meandered through the exhibits home to numerous species of reptiles and amphibians. Adults and children alike pressed their faces and hands up against the glass separating them from enclosures filled with lush greenery, water features and strikingly realistic murals. One Ozark hellbender, with its flat, mucus-coated body and short limbs, was putting on a show for the crowd. It pressed its body against the glass, floundering back and forth like a hypnotized cobra.

Jeff Ettling, curator of the Ron Goellner Center for Hellbender Conservation, bypassed the crowds and led the way down a hidden staircase to the basement. Ettling walked briskly through a maze of fish tanks and miscellaneous furniture unfazed by the foul-smelling, humid air and stepped into a sanitizing bleach bath.

Inside the center, nearly 4,000 Ozark and Eastern Hellbender salamanders squirmed in their tanks. Several racks stretched from floor to ceiling as keepers moved about, feeding the animals and changing the water. Even with the release of 2,454 hellbenders to the native streams and rivers of their parents to bolster wild populations, Ettling said there are so many at the zoo, the center is running out of space to house them all. It’s a problem that just a decade ago, Ettling didn’t expect to have.

When the hellbender conservation effort began in the early 2000s, there were less than 500 of the animals left in the wild, according to data from the Missouri Department of Conservation. Survival projections for the species looked grim when MDC, the St. Louis Zoo, and other collaborators set out to do something that had never been done in the world before: breed the hellbender in captivity.

Though the effort has been an unprecedented success, scientists are still looking to pinpoint what environmental factors are killing juveniles in the wild. Other amphibian populations throughout the world are quickly disappearing. As threats from habitat loss, disease and climate change continue to increase, it begs the question: Which species get to live?

The science experiment

Mimicking Mother Nature is no simple task. Ettling said he and the other collaborators had to think of the process like a 14-year science experiment. He said it required making controlled adjustments to their facilities to recreate the environment found in the wild as precisely as possible.

“We basically run these rooms like a bio-secure facility,” Ettling said of the hellbender center. “Because [hellbenders are] totally aquatic, we don’t have to worry about airborne contaminants like we would for terrestrial animals, but the water has to be perfect.”


The two 40-foot outdoor streams run outside the St. Louis Zoo Herpetarium on Tuesday, May 3, 2016. Ettling said the hellbenders use the streams to mate in the fall. Photo by Hannah Lazo.

The center has four mating streams, two inside and two outside. The streams contain gravel, fish and algae found in the Ozark streams and rivers. Hellbenders in the wild spend most their time living under large rocks at the bottom of the river. Hellbenders also mate under the protection of the rocks. Scientists at the zoo use boxes shaped like upside down basins to simulate the mating environment.

But after careful control for water temperature and light cycles, something was still off. By 2007, females were laying eggs, Ettling said, but the eggs weren’t being fertilized.

“We had to ask ourselves what was preventing the males from breeding,” Ettling said.

The scientists turned to scientific literature in search of a smoking gun and found a clue that changed the future outlook for the hellbender. Ettling said the team realized that the ion concentration of the water used at the zoo was much different than the water found in the Ozark streams.

Sperm samples from the males showed deformities and low motility, leading the team to think the ion concentration was to blame.

After a reverse osmosis filtration system was installed in July 2011, it didn’t take long before the situation began to change. Now, city water is purified and reconstituted to match the exact composition of Ozark water. By early October, sperm samples showed the highest motility recorded since the start of the program. Just 10 days later, one of the males fertilized a clutch of eggs in one of the outdoor streams.

Fertile Hellbender Eggs. Photo by Mark Wanner.

Fertilized hellbender eggs, like the ones discovered in 2011, sit in an egg tray. Th level of visible development inside the egg distinguishes them from unfertilized eggs. Photo courtesy of Mark Wanner.

On the day of the discovery, a freak thunderstorm kept MDC herpetologist Jeff Briggler from doing rattlesnake work in southern Missouri. Instead, as if by fate, he said he just showed up at the zoo unannounced. Though he’s involved in many other projects, Briggler plays a big role in the hellbender conservation effort and has been one of the driving forces behind the research. Briggler, Ettling and other members of the zoo staff were together to witness the first successful captive-breeding of hellbenders in the world.

“It’s just so odd that I was there randomly that day,” Briggler said. “When they flipped that lid I saw that first raceway full of eggs, I was so elated I just wanted to start calling everybody.”

Briggler and Ettling said that was the moment the two of them realized the future for the hellbender was looking much brighter.

Ettling said even greater success followed. In the fall of 2012, all three captive populations laid some 2,800 eggs resulting in 2,500 hatchlings. The zoo hellbenders have bred every year since, filling the hundreds of tanks in the Goellner Center to capacity.

Safety net in place, threats to survival remain in the wild

Hellbenders lead solitary lives, hiding under large rocks. With its gray-brown color and wrinkled skin, the salamanders can easily hide at the bottom of a stream bed. The Ozark Hellbender is unique because it is found only in the Ozark Mountains of Missouri and Arkansas.


A hellbender salamander lies on the bottom of a stream bed on July 13, 2012. Despite living their whole lives in the water, hellbenders don’t swim. They walk out of their hiding places at night to hunt. Photo courtesy of Brian Gratwicke. Used under the creative commons license.

Changes to the hellbender habitat are difficult to ignore. Historically, Briggler said the populations in the Ozarks reached upwards of 27,000. Today he estimates the habitat could support just 13,000.

In 2008, the first group of 36 captive-raised hellbenders were released at two points along the north fork of the White River in southern Missouri. Briggler said MDC was able to track the hellbenders locations using implanted radio transmitters and monitor their behavior. Not only were the hellbenders found to have established home ranges, the groups had survival rates of 75 and 48 percent, respectively.

Last year, Briggler said he and his team at MDC recaptured one of the males released in 2008 and found it had nearly tripled in weight. The animal was becoming reproductively mature, which happens between five and eight years of age. The next big milestone will be finding one of the zoo’s hellbenders guarding a nest of eggs. He thinks that could happen this year.

Still, Briggler has run the models and said he estimates the breeding program at the zoo will need to continue for about another 15 years.

“It sounds like a long time, but in reality, we started this in 2004 and it look 12 years to get where we are today,” Ettling said. “Depending on what the survival rate is, it may extend even further than that.”

Some unaddressed concerns remain for the future of the hellbender. Research has been inconclusive in determining which environmental factors are impacting younger salamanders in the wild. Ettling said researchers have more questions than answers, but they suspect that increased sedimentation, a byproduct of activities like logging and runoff from surrounding land, is burying the large rocks on the river bottom where hellbenders spend most of their lives hiding. The result is that hellbenders, which are territorial, are forced to live much closer together than is preferable. Ettling said some males will fight each other.

“Change happens,” Briggler said. “It’s just sometimes not the best.”

Another concern is chytrid fungus, blamed for wiping out many amphibian species to date. Ettling said there are hundreds of types of chytrid. Some strains are harmless, like the ones that breaks down leaf litter. One strain, known as Bd, has proven capable of infecting almost all of the world’s amphibian species. Bd causes amphibian skin to harden and creates wounds ripe for secondary infections. Since salamanders breathe through their skin, a fungus that impacts a salamander’s flesh is particularly problematic.

Chytrid fungus is a global problem. It has been found on three continents, according to Karen Lips, a conservation biology expert at the University of Maryland. Approximately 43 percent of the 7,500 known amphibian species are in decline and approximately 32 percent are threatened.

Climate change is expected to impact the hellbender as well, according to Briggler. But it will depend on how well the cold-water-adapted hellbender can tolerate warmer water. If they can, he said it may help to clear off some the chytrid fungus. There is no guarantee, though. Briggler said it’s important to protect the riparian corridor along the river’s edges. The corridor is made up of unique vegetation growing near the water.

“The more shade there is, the cooler the water stays,” he said.

An ethical dilemma

Lips said amphibians occupy an important place within the ecosystems they inhabit. They eat insects and smaller animals and larger animals eat them. If the amphibians are impacted by a change in the environment, there’s a good chance it could impact other vertebrates and even humans down the road.

At the annual AAAS conference in Washington D.C. in February, Lips spoke about the ethical dilemma that emerges as more and more species become threatened. The reality, she said, is that not every species can be saved, forcing people to chose which ones get to live. Is it the rare species? Is it the most useful species? Who makes that decision?


There’s not one checklist of questions to use when making these conservation decisions, Lips said. But a common consideration seems to be if the decline of a species is human-caused, then we should do something about it. If it is a natural die-off, then we shouldn’t.
“The problem today is that human activity has had such drastic impacts on the natural world, it is hard to distinguish what is anthropogenic or natural,” Lips said at the conference.
Briggler said many difficult questions must be asked and answered before any decision can be reached – questions like how abundant the species was before, what can be done to save it, and if the right people are in place to do the job, to name a few.
The hellbender was added to the Missouri state endangered species list in 2003. Though it wasn’t the only animal on the list, it was prioritized for the captive breeding effort because of the multitude of threats in the wild. If no action had been taken, there’s a good chance the hellbender could have disappeared within 20 years, Briggler said.

He said the zoo and MDC are fortunate to have had a talented staff in place to carry out the intervention. They also had the resources needed. He said his department spends between $50,000 to $250,000 each year depending on other research projects taking place. Briggler said many private citizens donated, too.  If the funding for conservation efforts such as this can’t be secured, the grim reality is that nothing can be done.

“I think about all the species in Missouri and try to make sure everyone of them is still here when I retire,” Briggler said. “Now, I think they will be, but you never know.”

Looking ahead

On a typical Tuesday at the St. Louis Zoo, thousands of hellbenders squirmed in their tanks as Ettling walked up and down each row in a state of quiet admiration. Some of the larger ones hid inside pieces of PVC pipe while smaller ones bobbed around in the bubbles coming from the top of the tank.

Augmentation and studies of captive-raised hellbenders will continue in the coming years. Briggler said he and other MDC scientists comb the rivers in search of the elusive hellbender, ready to take blood samples and check for diseases and pollutants to add to their database.

He said he and his coworkers will need time and patience to collect enough data as is needed without disrupting the habitat more than is necessary. The first rule of reintroduction, he said, is to do no harm to existing populations.

“How would you like to be harassed in your home all the time?” Briggler said. “We don’t want to be like the paparazzi out there.”

Meticulous planning goes into every augmentation. Briggler said the MDC has to make sure the animals put back out in the wild are not too closely related to preserve genetic variety.

The reality is that not every hellbender raised at the zoo will be released into the wild. Some will be used for research purposes.

“We may have to infect some of the babies (with diseases) because we can’t learn that in the wild,” Briggler said.

It’s a necessary action to learn how diseases are impacting juveniles, he said. At an inch and a half in length, baby hellbenders are too small to implant with trackers, making them even more difficult to find once released. Briggler said he’s been lucky to catch six babies in the last four to five years.

“I hope the end of the story is that are working on a different animal at the end of our careers,” Briggler said of the hellbenders, “because that means we saved it.”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s